It is generally believed that job satisfaction increases linearly with age. However, there are persuasive arguments, and some empirical evidence, that the relationship is U‐shaped, declining from a moderate level in the early years of employment and then increasing steadily up to retirement. This paper investigates that relationship, using survey responses from a large sample of British employees. For overall job satisfaction, satisfaction with pay, and satisfaction with the work itself, a strongly significant U‐shape is observed. Ordered probit techniques, which take account of the ordinality of satisfaction data, are used to analyse the relationship between these forms of satisfaction and a large set of individual and job characteristics. Despite the inclusion of 80 control variables, significant coefficients persist for the age and age‐squared variables (the latter representing the non‐linear component). The paper thus provides strong evidence for a U‐shaped relationship between age and job satisfaction. Furthermore, it is shown that a similar age pattern occurs for employees' context‐free mental health, suggesting that both job satisfaction and context‐free mental health are affected by non‐job factors of life‐stage and personal circumstances. The importance of changes in expectations with increasing